1. Field of the Invention
This invention relates generally to ball valves, and more particularly to apparatus and a method for replacement of the downstream seal of such valves.
2. Description of the Prior Art
Ball valve assemblies are widely used in piping systems. Typically they have a valve body with a passageway through it and which opens at opposite flanged faces of the valve body, with the opening at the center of the face and a large flange with bolt receiving holes by which the valve body can be bolted to flange piping. Such valves are often used in a system in which the flow is usually in one direction from an upstream, higher pressure side to a downstream side. However, it is not uncommon for ball valves to be used in systems in which the pressure differential across the valve can be in opposite directions at different times.
When such valves are used on fittings to enable supply of material to or removal of material from a tank, such as on a tanker truck or railroad car, occasions arise when it is desirable to replace one or both seals. If the application is in a tanker wherein there is piping or a hose external to the valve assembly to supply material to the tank or remove it from the tank, but not always in place, it is desirable to be able to replace the outboard valve seal without emptying the tank. In other words, it is desirable to be able to replace the outboard seal even if there is pressure in the tank. Heretofore, to the best of my knowledge, that has not been possible in conventional ball valve assemblies, without removing the pressure from the tank. In many instances, has necessitated draining the product from the tank before seal replacement. Therefore, it is an object of the present invention to facilitate removal of the outboard seal from a ball valve assembly, and replacement of the seal, while the tank or plumbing line upstream of the valve body remains pressurized.